1. Field of the Invention
The present application relates to magnetic resonance (MR) imaging system, and more specifically to MR Imaging system which allows access to the patient during imaging.
2. Description of Related Art
In Magnetic Resonance (MR) Imaging magnetic field gradients are produced over a patient desired to be imaged by energizing gradient coils which produce magnetic fields which interact with a static magnetic field produced by a main magnet. Radiofrequency (RF) excitation pulses produce RF energy which is radiated through the patient, nutating resonating nuclei "nuclear spins". These nutated nuclear spins produce a spatially dependent MR response signal when proper readout magnetic field gradients are applied to them. In order to produce accurate images, the main magnetic field must be spatially homogeneous over the imaging region. Also, the magnetic field gradients must also be spatially homogeneous.
Typically, to produce a homogeneous magnetic field over the patient, the main magnet has a cylindrical shape which surrounds the patient. The gradient coils are also cylindrically shaped and fit inside the main magnetic and also surround the patient. Access to the patient is, therefore, severely limited due to the geometry of the magnet and gradient coils. In addition to limited access, patients typically develop a claustrophobic reaction during imaging.
In order to provide MR images of a patient in conventional systems, the three dimensional position and orientation of a desired region of the patient to be imaged must be provided to the MR imaging system. The three dimensional orientation must also be provided, in addition to the location. These orientations must be calculated manually. Even though the computations may not be difficult, it makes it cumbersome to produce several images at different orientations.
Currently there is a need for an MR imaging system which provides MR images of selected internal structures of a patient undergoing a medical procedure in which a physician may easily indicate a desired region and a desired viewing angle.